/*
** $Id: lstate.h $
** Global State
** See Copyright Notice in lua.h
*/

#ifndef lstate_h
#define lstate_h

#include "lua.h"

#include "lobject.h"
#include "ltm.h"
#include "lzio.h"

/*
** Some notes about garbage-collected objects: All objects in Lua must
** be kept somehow accessible until being freed, so all objects always
** belong to one (and only one) of these lists, using field 'next' of
** the 'CommonHeader' for the link:
**
** 'allgc': all objects not marked for finalization;
** 'finobj': all objects marked for finalization;
** 'tobefnz': all objects ready to be finalized;
** 'fixedgc': all objects that are not to be collected (currently
** only small strings, such as reserved words).
**
** For the generational collector, some of these lists have marks for
** generations. Each mark points to the first element in the list for
** that particular generation; that generation goes until the next mark.
**
** 'allgc' -> 'survival': new objects;
** 'survival' -> 'old': objects that survived one collection;
** 'old1' -> 'reallyold': objects that became old in last collection;
** 'reallyold' -> NULL: objects old for more than one cycle.
**
** 'finobj' -> 'finobjsur': new objects marked for finalization;
** 'finobjsur' -> 'finobjold1': survived   """";
** 'finobjold1' -> 'finobjrold': just old  """";
** 'finobjrold' -> NULL: really old       """".
**
** All lists can contain elements older than their main ages, due
** to 'luaC_checkfinalizer' and 'udata2finalize', which move
** objects between the normal lists and the "marked for finalization"
** lists. Moreover, barriers can age young objects in young lists as
** OLD0, which then become OLD1. However, a list never contains
** elements younger than their main ages.
**
** The generational collector also uses a pointer 'firstold1', which
** points to the first OLD1 object in the list. It is used to optimize
** 'markold'. (Potentially OLD1 objects can be anywhere between 'allgc'
** and 'reallyold', but often the list has no OLD1 objects or they are
** after 'old1'.) Note the difference between it and 'old1':
** 'firstold1': no OLD1 objects before this point; there can be all
**   ages after it.
** 'old1': no objects younger than OLD1 after this point.
*/

/*
** Moreover, there is another set of lists that control gray objects.
** These lists are linked by fields 'gclist'. (All objects that
** can become gray have such a field. The field is not the same
** in all objects, but it always has this name.)  Any gray object
** must belong to one of these lists, and all objects in these lists
** must be gray (with two exceptions explained below):
**
** 'gray': regular gray objects, still waiting to be visited.
** 'grayagain': objects that must be revisited at the atomic phase.
**   That includes
**   - black objects got in a write barrier;
**   - all kinds of weak tables during propagation phase;
**   - all threads.
** 'weak': tables with weak values to be cleared;
** 'ephemeron': ephemeron tables with white->white entries;
** 'allweak': tables with weak keys and/or weak values to be cleared.
**
** The exceptions to that "gray rule" are:
** - TOUCHED2 objects in generational mode stay in a gray list (because
** they must be visited again at the end of the cycle), but they are
** marked black because assignments to them must activate barriers (to
** move them back to TOUCHED1).
** - Open upvales are kept gray to avoid barriers, but they stay out
** of gray lists. (They don't even have a 'gclist' field.)
*/

/*
** About 'nCcalls':  This count has two parts: the lower 16 bits counts
** the number of recursive invocations in the C stack; the higher
** 16 bits counts the number of non-yieldable calls in the stack.
** (They are together so that we can change and save both with one
** instruction.)
*/

/* true if this thread does not have non-yieldable calls in the stack */
#define yieldable(L) (((L)->nCcalls & 0xffff0000) == 0)

/* real number of C calls */
#define getCcalls(L) ((L)->nCcalls & 0xffff)

/* Increment the number of non-yieldable calls */
#define incnny(L)    ((L)->nCcalls += 0x10000)

/* Decrement the number of non-yieldable calls */
#define decnny(L)    ((L)->nCcalls -= 0x10000)

/* Non-yieldable call increment */
#define nyci         (0x10000 | 1)

struct lua_longjmp; /* defined in ldo.c */

/*
** Atomic type (relative to signals) to better ensure that 'lua_sethook'
** is thread safe
*/
#if !defined(l_signalT)
// #include <signal.h>
// #define l_signalT sig_atomic_t
#define l_signalT int
#endif

/*
** Extra stack space to handle TM calls and some other extras. This
** space is not included in 'stack_last'. It is used only to avoid stack
** checks, either because the element will be promptly popped or because
** there will be a stack check soon after the push. Function frames
** never use this extra space, so it does not need to be kept clean.
*/
#define EXTRA_STACK      5

#define BASIC_STACK_SIZE (2 * LUA_MINSTACK)

#define stacksize(th)    cast_int((th)->stack_last - (th)->stack)

/* kinds of Garbage Collection */
#define KGC_INC          0 /* incremental gc */
#define KGC_GEN          1 /* generational gc */

typedef struct stringtable {
    TString **hash;
    int nuse; /* number of elements */
    int size;
} stringtable;

/*
** Information about a call.
** About union 'u':
** - field 'l' is used only for Lua functions;
** - field 'c' is used only for C functions.
** About union 'u2':
** - field 'funcidx' is used only by C functions while doing a
** protected call;
** - field 'nyield' is used only while a function is "doing" an
** yield (from the yield until the next resume);
** - field 'nres' is used only while closing tbc variables when
** returning from a function;
** - field 'transferinfo' is used only during call/returnhooks,
** before the function starts or after it ends.
*/
typedef struct CallInfo {
    StkId func;                       /* function index in the stack */
    StkId top;                        /* top for this function */
    struct CallInfo *previous, *next; /* dynamic call link */
    union {
        struct { /* only for Lua functions */
            const Instruction *savedpc;
            volatile l_signalT trap;
            int nextraargs; /* # of extra arguments in vararg functions */
        } l;
        struct {             /* only for C functions */
            lua_KFunction k; /* continuation in case of yields */
            ptrdiff_t old_errfunc;
            lua_KContext ctx; /* context info. in case of yields */
        } c;
    } u;
    union {
        int funcidx;                  /* called-function index */
        int nyield;                   /* number of values yielded */
        int nres;                     /* number of values returned */
        struct {                      /* info about transferred values (for call/return hooks) */
            unsigned short ftransfer; /* offset of first value transferred */
            unsigned short ntransfer; /* number of values transferred */
        } transferinfo;
    } u2;
    short nresults; /* expected number of results from this function */
    unsigned short callstatus;
} CallInfo;

/*
** Bits in CallInfo status
*/
#define CIST_OAH       (1 << 0) /* original value of 'allowhook' */
#define CIST_C         (1 << 1) /* call is running a C function */
#define CIST_FRESH     (1 << 2) /* call is on a fresh "luaV_execute" frame */
#define CIST_HOOKED    (1 << 3) /* call is running a debug hook */
#define CIST_YPCALL    (1 << 4) /* doing a yieldable protected call */
#define CIST_TAIL      (1 << 5) /* call was tail called */
#define CIST_HOOKYIELD (1 << 6) /* last hook called yielded */
#define CIST_FIN       (1 << 7) /* function "called" a finalizer */
#define CIST_TRAN      (1 << 8) /* 'ci' has transfer information */
#define CIST_CLSRET    (1 << 9) /* function is closing tbc variables */
/* Bits 10-12 are used for CIST_RECST (see below) */
#define CIST_RECST     10
#if defined(LUA_COMPAT_LT_LE)
#define CIST_LEQ (1 << 13) /* using __lt for __le */
#endif

/*
** Field CIST_RECST stores the "recover status", used to keep the error
** status while closing to-be-closed variables in coroutines, so that
** Lua can correctly resume after an yield from a __close method called
** because of an error.  (Three bits are enough for error status.)
*/
#define getcistrecst(ci) (((ci)->callstatus >> CIST_RECST) & 7)
#define setcistrecst(ci, st)                                        \
    check_exp(((st)&7) == (st), /* status must fit in three bits */ \
              ((ci)->callstatus = ((ci)->callstatus & ~(7 << CIST_RECST)) | ((st) << CIST_RECST)))

/* active function is a Lua function */
#define isLua(ci)     (!((ci)->callstatus & CIST_C))

/* call is running Lua code (not a hook) */
#define isLuacode(ci) (!((ci)->callstatus & (CIST_C | CIST_HOOKED)))

/* assume that CIST_OAH has offset 0 and that 'v' is strictly 0/1 */
#define setoah(st, v) ((st) = ((st) & ~CIST_OAH) | (v))
#define getoah(st)    ((st)&CIST_OAH)

/*
** 'global state', shared by all threads of this state
*/
typedef struct global_State {
    lua_Alloc frealloc; /* function to reallocate memory */
    void *ud;           /* auxiliary data to 'frealloc' */
    l_mem totalbytes;   /* number of bytes currently allocated - GCdebt */
    l_mem GCdebt;       /* bytes allocated not yet compensated by the collector */
    lu_mem GCestimate;  /* an estimate of the non-garbage memory in use */
    lu_mem lastatomic;  /* see function 'genstep' in file 'lgc.c' */
    stringtable strt;   /* hash table for strings */
    TValue l_registry;
    TValue nilvalue;   /* a nil value */
    unsigned int seed; /* randomized seed for hashes */
    lu_byte currentwhite;
    lu_byte gcstate;     /* state of garbage collector */
    lu_byte gckind;      /* kind of GC running */
    lu_byte gcstopem;    /* stops emergency collections */
    lu_byte genminormul; /* control for minor generational collections */
    lu_byte genmajormul; /* control for major generational collections */
    lu_byte gcstp;       /* control whether GC is running */
    lu_byte gcemergency; /* true if this is an emergency collection */
    lu_byte gcpause;     /* size of pause between successive GCs */
    lu_byte gcstepmul;   /* GC "speed" */
    lu_byte gcstepsize;  /* (log2 of) GC granularity */
    GCObject *allgc;     /* list of all collectable objects */
    GCObject **sweepgc;  /* current position of sweep in list */
    GCObject *finobj;    /* list of collectable objects with finalizers */
    GCObject *gray;      /* list of gray objects */
    GCObject *grayagain; /* list of objects to be traversed atomically */
    GCObject *weak;      /* list of tables with weak values */
    GCObject *ephemeron; /* list of ephemeron tables (weak keys) */
    GCObject *allweak;   /* list of all-weak tables */
    GCObject *tobefnz;   /* list of userdata to be GC */
    GCObject *fixedgc;   /* list of objects not to be collected */
    /* fields for generational collector */
    GCObject *survival;      /* start of objects that survived one GC cycle */
    GCObject *old1;          /* start of old1 objects */
    GCObject *reallyold;     /* objects more than one cycle old ("really old") */
    GCObject *firstold1;     /* first OLD1 object in the list (if any) */
    GCObject *finobjsur;     /* list of survival objects with finalizers */
    GCObject *finobjold1;    /* list of old1 objects with finalizers */
    GCObject *finobjrold;    /* list of really old objects with finalizers */
    struct lua_State *twups; /* list of threads with open upvalues */
    lua_CFunction panic;     /* to be called in unprotected errors */
    struct lua_State *mainthread;
    TString *memerrmsg;                        /* message for memory-allocation errors */
    TString *tmname[TM_N];                     /* array with tag-method names */
    struct Table *mt[LUA_NUMTAGS];             /* metatables for basic types */
    TString *strcache[STRCACHE_N][STRCACHE_M]; /* cache for strings in API */
    lua_WarnFunction warnf;                    /* warning function */
    void *ud_warn;                             /* auxiliary data to 'warnf' */
} global_State;

/*
** 'per thread' state
*/
struct lua_State {
    CommonHeader;
    lu_byte status;
    lu_byte allowhook;
    unsigned short nci; /* number of items in 'ci' list */
    StkId top;          /* first free slot in the stack */
    global_State *l_G;
    CallInfo *ci;     /* call info for current function */
    StkId stack_last; /* end of stack (last element + 1) */
    StkId stack;      /* stack base */
    UpVal *openupval; /* list of open upvalues in this stack */
    StkId tbclist;    /* list of to-be-closed variables */
    GCObject *gclist;
    struct lua_State *twups;      /* list of threads with open upvalues */
    struct lua_longjmp *errorJmp; /* current error recover point */
    CallInfo base_ci;             /* CallInfo for first level (C calling Lua) */
    volatile lua_Hook hook;
    ptrdiff_t errfunc; /* current error handling function (stack index) */
    l_uint32 nCcalls;  /* number of nested (non-yieldable | C)  calls */
    int oldpc;         /* last pc traced */
    int basehookcount;
    int hookcount;
    volatile l_signalT hookmask;
};

#define G(L)             (L->l_G)

/*
** 'g->nilvalue' being a nil value flags that the state was completely
** build.
*/
#define completestate(g) ttisnil(&g->nilvalue)

/*
** Union of all collectable objects (only for conversions)
** ISO C99, 6.5.2.3 p.5:
** "if a union contains several structures that share a common initial
** sequence [...], and if the union object currently contains one
** of these structures, it is permitted to inspect the common initial
** part of any of them anywhere that a declaration of the complete type
** of the union is visible."
*/
union GCUnion {
    GCObject gc; /* common header */
    struct TString ts;
    struct Udata u;
    union Closure cl;
    struct Table h;
    struct Proto p;
    struct lua_State th; /* thread */
    struct UpVal upv;
};

/*
** ISO C99, 6.7.2.1 p.14:
** "A pointer to a union object, suitably converted, points to each of
** its members [...], and vice versa."
*/
#define cast_u(o) cast(union GCUnion *, (o))

/* macros to convert a GCObject into a specific value */
#define gco2ts(o) \
    check_exp(novariant((o)->tt) == LUA_TSTRING, &((cast_u(o))->ts))
#define gco2u(o)   check_exp((o)->tt == LUA_VUSERDATA, &((cast_u(o))->u))
#define gco2lcl(o) check_exp((o)->tt == LUA_VLCL, &((cast_u(o))->cl.l))
#define gco2ccl(o) check_exp((o)->tt == LUA_VCCL, &((cast_u(o))->cl.c))
#define gco2cl(o) \
    check_exp(novariant((o)->tt) == LUA_TFUNCTION, &((cast_u(o))->cl))
#define gco2t(o)         check_exp((o)->tt == LUA_VTABLE, &((cast_u(o))->h))
#define gco2p(o)         check_exp((o)->tt == LUA_VPROTO, &((cast_u(o))->p))
#define gco2th(o)        check_exp((o)->tt == LUA_VTHREAD, &((cast_u(o))->th))
#define gco2upv(o)       check_exp((o)->tt == LUA_VUPVAL, &((cast_u(o))->upv))

/*
** macro to convert a Lua object into a GCObject
** (The access to 'tt' tries to ensure that 'v' is actually a Lua object.)
*/
#define obj2gco(v)       check_exp((v)->tt >= LUA_TSTRING, &(cast_u(v)->gc))

/* actual number of total bytes allocated */
#define gettotalbytes(g) cast(lu_mem, (g)->totalbytes + (g)->GCdebt)

LUAI_FUNC void luaE_setdebt(global_State *g, l_mem debt);
LUAI_FUNC void luaE_freethread(lua_State *L, lua_State *L1);
LUAI_FUNC CallInfo *luaE_extendCI(lua_State *L);
LUAI_FUNC void luaE_freeCI(lua_State *L);
LUAI_FUNC void luaE_shrinkCI(lua_State *L);
LUAI_FUNC void luaE_checkcstack(lua_State *L);
LUAI_FUNC void luaE_incCstack(lua_State *L);
LUAI_FUNC void luaE_warning(lua_State *L, const char *msg, int tocont);
LUAI_FUNC void luaE_warnerror(lua_State *L, const char *where);
LUAI_FUNC int luaE_resetthread(lua_State *L, int status);

#endif
